Processing apparatus and method for achieving process damping therein

Abstract

To make it possible to effectively improve production efficiency and manufacture easily and economically with simple configuration.SOLUTION: A tip 24 and a flat plate-like member 26 are attached to a boring bar 12. The tip 24 is detachably attached via a clamp block 38, and the flat plate-like member 26 is positioned in the rear of a flank 24b of the tip 24 and is detachably attached by a fixed bolt 28. A distance T between a tip 26a of the flat plate-like member 26 in a processing radial direction and an inner peripheral surface Wa of the work-piece after processing by the tip 24 is set within a range of 3 microns≤T≤10 microns.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a machining apparatus in which a blade tool for internal diameter machining is attached to a boring bar via a clamp mechanism. Background Art

[0002] In general, various types of machine tools are used for performing machining on a workpiece via a machining tool. For example, boring is performed by attaching a boring bar provided with a boring cutter (cutting edge) to the rotating spindle of a machine tool, and sequentially feeding the boring bar along a prepared hole while rotating the boring bar at high speed, thereby machining a highly accurate hole at a predetermined position with the cutting edge machining diameter.

[0003] In this type of machining apparatus, deflection due to cutting resistance is likely to occur in the rotating spindle, the machining tool, and the workpiece. Vibration is induced in the machining tool and the workpiece due to this deflection, and this vibration may become chatter (including so-called regenerative chatter) and appear in machining. In particular, when machining a mold with a considerably long tool, or when efficiently machining difficult-to-cut materials, suppressing or avoiding chatter is a major issue.

[0004] Therefore, as one countermeasure against chatter (anti-vibration countermeasure), a method of exerting a so-called process damping effect is known. This process damping is a phenomenon in which when chatter vibration occurs during cutting, the flank of the machining tool comes into contact with the vibrating machined surface of the workpiece to generate a damping effect (vibration damping force).

[0005] Specifically, as shown in Figure 9, when machining a workpiece (material to be cut) 2 using a chip (machining tool) 1, machining vibrations, mainly caused by natural vibrations, are likely to occur. As the amplitude of the cutting vibration waveform generated in the workpiece 2 increases, the flank surface 3 of the chip 1 comes into contact with the peak portion of the cutting vibration waveform, resulting in a damping effect. However, the above-mentioned process damping effect is only applicable in the low-speed rotation range where the vibration wavelength is short, which makes it difficult to increase the machining allowance or feed rate, for example, and leads to a decrease in machining production efficiency.

[0006] Therefore, for example, a special chamfering process is applied to the relief surface of the chip, and a large damping effect is provided when the machined surface of the workpiece comes into contact with the chamfered relief surface of the chip. This type of technology can be implemented, for example, by referring to the cutting tool disclosed in Patent Document 1.

[0007] This cutting tool has an active main blade that penetrates the circular hole in the workpiece, and a secondary blade is provided at the outermost end of the active main blade, with a secondary blade relief surface connected to the secondary blade. Furthermore, a support portion is provided on the secondary blade relief surface, and the rotational radius of the support portion is set to protrude more than the flight circle radius of the active main blade. As a result, the cutting tool is already supported during the drilling process, and smoothing and refinement of the machined surface in the region of the hole wall is achieved. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 2011-529801 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, in the above-mentioned Patent Document 1, the support portion is in constant contact with the machined surface of the workpiece after processing to smooth the machined surface, and therefore a good process damping effect cannot be obtained. Moreover, it has the problem of complicating the processing of the cutting tool itself, lacking versatility, and being uneconomical.

[0010] The present invention aims to solve this type of problem and to provide a processing apparatus and a method for achieving process damping therein that can effectively improve production efficiency with a simple configuration and can be manufactured easily and economically. [Means for solving the problem]

[0011] The machining apparatus according to the present invention comprises a boring bar, a cutting tool for internal diameter machining, a flat plate-shaped member, and a fixing mechanism. The cutting tool is detachably attached to the boring bar via a clamping mechanism. The flat plate-shaped member is detachably attached to the boring bar, positioned behind the relief surface of the cutting tool. The fixing mechanism fixes the flat plate-shaped member to the boring bar so that its position can be adjusted in the machining diameter direction by the cutting tool. The distance T between the tip of the flat plate-shaped member in the machining diameter direction and the inner circumferential surface of the workpiece after machining by the cutting tool is set within the range of 3 microns (μm) ≤ T ≤ 10 microns (μm). Furthermore, by setting the distance T within the range of 3 microns (μm) ≤ T ≤ 10 microns (μm), process damping is introduced at the tip in the machining diameter direction. [Effects of the Invention]

[0012] In this invention, a flat plate-shaped member is attached to the rear of the relief surface of the cutting tool, and the distance between the tip of the flat plate-shaped member in the machining radial direction and the inner circumferential surface of the workpiece after machining by the cutting tool is set within the range of 3 to 10 microns. Therefore, when the amplitude of the cutting vibration waveform generated during inner diameter machining by the cutting tool becomes large, the tip of the flat plate-shaped member in the machining radial direction comes into contact with the peak portion of the cutting vibration waveform. Consequently, a damping effect is achieved, and a good vibration isolation effect can be obtained. As a result, with a simple configuration, it becomes possible to increase the machining allowance or feed rate, for example, effectively improve production efficiency, and it becomes possible to manufacture easily and economically. Moreover, process damping can be effectively achieved at the tip in the machining radial direction. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view illustrating the main part of the boring bar tip side that constitutes the processing apparatus according to the first embodiment of the present invention. [Figure 2] This is a perspective view illustrating the main part of the boring bar tip with the clamp block removed. [Figure 3] This is a cross-sectional diagram illustrating the tip side of the boring bar. [Figure 4] This is a cross-sectional diagram of the clamp block. [Figure 5] This is an enlarged view of the main part at the tip of the boring bar. [Figure 6] This is an explanatory diagram of the flat plate-shaped member attached to the boring bar. [Figure 7] This is a cross-sectional diagram illustrating the main part of the tip side of a boring bar that constitutes a processing apparatus according to a second embodiment of the present invention. [Figure 8] This is a cross-sectional diagram illustrating the main part of the tip side of a boring bar that constitutes a processing apparatus according to the third embodiment of the present invention. [Figure 9] This is a diagram illustrating general process dumping. [Modes for carrying out the invention]

[0014] As shown in Figs. 1 to 3, a processing apparatus 10 according to a first embodiment of the present invention includes a boring bar 12, and the boring bar 12 is detachably attached to a spindle (main shaft) not shown. Note that the boring bar 12 may be configured not only to be used as a rotating tool but also to perform processing by rotating a workpiece W that is an object to be processed.

[0015] As shown in Fig. 2, at the tip end of the boring bar 12, a first wall surface 14a is formed by cutting inward from the outer periphery of the boring bar 12 in the processing radial direction (arrow R direction). A second wall surface 14b orthogonal to the first wall surface 14a is formed at the inner end of the first wall surface 14a, and a fourth wall surface 14d orthogonal to the second wall surface 14b is formed at the rear end of the second wall surface 14b via a curved third wall surface 14c.

[0016] The first wall surface 14a extends in a rotation axis direction (processing axis direction) (arrow L direction) intersecting the processing radial direction of the boring bar 12, and a cartridge mounting recess 16 is formed at the front end of the first wall surface 14a. As shown in Fig. 3, a first bolt hole 18a and a second bolt hole 18b are formed on a bottom surface 16a of the cartridge mounting recess 16.

[0017] As shown in Fig. 2, a clamp bolt hole 20 is formed in the first wall surface 14a at a position rearward of the cartridge mounting recess 16. As shown in Fig. 4, the axis of the clamp bolt hole 20 is inclined by an angle γ toward the side away from the third wall surface 14c with respect to a vertical line V perpendicular to the first wall surface 14a. A clamp recess 22 is formed at the rear edge of the first wall surface 14a. As shown in Fig. 2, the clamp recess 22 has a substantially triangular shape, and the wall surface on the clamp bolt hole 20 side constitutes an inclined surface 22a. The inclined surface 22a is inclined inward toward the third wall surface 14c (see Fig. 4).

[0018] As shown in Figs. 2 and 3, a cutting insert (cutting tool) 24 for internal diameter machining, a flat plate member 26, a fixing bolt (fixing mechanism) 28 for fixing the flat plate member 26 to a boring bar 12 in such a manner that the position thereof can be adjusted in the machining radial direction, and an actuating mechanism 30 capable of correcting the position of the cutting insert 24 in the machining radial direction are mounted in the recess 16 for cartridge mounting. For example, the cutting insert 24 has a rectangular shape, a guide hole portion 32 is formed at the center, and a tapered hole portion 34 is coaxially communicated with the upper end side of the guide hole portion 32.

[0019] As shown in Figs. 3 and 5, the cutting insert 24 has an insert tip (machining point) 24a that protrudes to the outermost side in the machining radial direction at the tip, and a flank face 24b set to an insert relief angle α is provided from the insert tip 24a toward the rear in the machining direction (direction of arrow F). As the cutting insert 24, it is preferable to use a positive insert in which the insert relief angle α is, for example, up to 8 degrees.

[0020] The flat plate member 26 is set to a shape corresponding to the shape of the cutting insert 24, and has, for example, a rectangular shape with a uniform thickness in the machining direction. The flat plate member 26 is positioned behind the flank face 24b of the cutting insert 24, and is detachably attached to the bottom surface 16a of the recess 16 for cartridge mounting in a state of being superimposed on the cutting insert 24. As shown in Fig. 6, at least a part of the machining radial direction tip portion 26a of the flat plate member 26 is configured to have an R-shaped cross section, and for example, is partially formed into an R-shape with different curvature radii. The distance T between the machining radial direction tip portion 26a and the machined inner peripheral surface Wa of the workpiece formed by the cutting insert 24 is set within a range of 3 microns (μm) ≦ T ≦ 10 microns (μm). More preferably, the distance T is set within a range of 5 microns (μm) ≦ T ≦ 10 microns (μm).

[0021] As shown in Figure 5, a hole 36 is formed in the center of the flat plate-shaped member 26, and a fixing bolt 28 that loosely fits into this hole 36 is screwed into the first bolt hole 18a. The diameter of the fixing bolt 28 is set to be smaller than the opening diameter of the hole 36, and the flat plate-shaped member 26 fixed to the fixing bolt 28 is adjustable in the machining diameter direction. The head 28a of the fixing bolt 28 is inserted into the guide hole 32 of the tip 24 and functions as a mounting guide for the tip 24.

[0022] The tip 24 is detachably attached to the boring bar 12 via a clamp block (clamping mechanism) 38. As shown in Figure 1, the clamp block 38 covers the first wall surface 14a and has a shape that follows the second wall surfaces 14b to the fourth wall surfaces 14d. As shown in Figure 4, a stepped hole 40 with an inclined surface is formed on the central side of the clamp block 38, into which a clamp bolt 41 is inserted, and the clamp bolt 41 is screwed into the clamp bolt hole 20. A wrench hole 42 is formed near the corner of the clamp block 38 that is close to the second wall surface 14b (see Figures 1 and 3).

[0023] As shown in Figure 4, the bottom surface of the clamp block 38 is provided with a curved projection 44 that fits into the tapered hole 34 of the tip 24, and a claw portion 46 that engages with the clamp recess 22 of the first wall surface 14a. The claw portion 46 has an inclined surface portion 46a that contacts the inclined surface 22a of the clamp recess 22.

[0024] As shown in Figures 2 and 3, the operating mechanism 30 comprises a tapered prism member 48 having a substantially rectangular prism shape, and an adjustment bolt 50 that moves the tapered prism member 48 back and forth along the side surface 16b of the cartridge mounting recess 16. The tapered prism member 48 has a tapered surface 48a that is inclined outward (towards the tip 24) toward the bottom surface 16a of the cartridge mounting recess 16 and contacts the inclined surface 24c of the tip 24, and a screw hole 48b that penetrates in the thickness direction.

[0025] The adjustment bolt 50 has a first threaded portion 52a and a second threaded portion 52b arranged coaxially. The first threaded portion 52a is screwed into the threaded hole 48b of the tapered piece member 48, while the second threaded portion 52b is screwed into the second bolt hole 18b of the cartridge mounting recess 16. The pitch of the first threaded portion 52a is set to a value greater than the pitch of the second threaded portion 52b, so that when the adjustment bolt 50 is rotated in the forward direction, the pitch difference pushes the tapered piece member 48 upward in a direction away from the bottom surface 16a. A pressing spring may be interposed between the bottom surface 16a and the tapered piece member 48.

[0026] The operation of the processing apparatus 10 according to the first embodiment, configured in this manner, will be described below.

[0027] As shown in Figure 3, when the spindle constituting the machining apparatus 10 is driven to rotate in the direction of arrow F, the boring bar 12 rotates in the direction of arrow F together with the spindle. A tip 24 is attached to the boring bar 12, and under the rotational action of the boring bar 12, the tip 24a of the tip 24 machines the inner circumferential surface Wf of the workpiece W (inner diameter machining). At that time, coolant may be supplied to the upper surface of the flat plate-shaped member 26 to prevent cutting chips and the like from entering the clearance between the flat plate-shaped member 26 and the workpiece W. Alternatively, the workpiece W may be rotated in the opposite direction to the direction of arrow F without rotating the boring bar 12.

[0028] When the inner diameter of the workpiece W is machined by the chip 24, a portion of the relief surface 24b of the chip 24 contacts the inner circumferential surface Wa of the workpiece W after machining, resulting in a damping effect, i.e., a process damping effect. However, depending on the installation state of the chip 24 and the relief angle, the relief surface 24b may not contact the inner circumferential surface Wa of the workpiece W after machining.

[0029] In this case, in the first embodiment, the distance T between the radially processed tip 26a of the flat plate-shaped member 26 and the inner circumferential surface Wa of the workpiece after machining by the chip 24 is set within the range of 3 microns (μm) ≤ T ≤ 10 microns (μm), more preferably within the range of 5 microns (μm) ≤ T ≤ 10 microns (μm). Therefore, when the amplitude of the cutting vibration waveform generated during inner diameter machining by the chip 24 becomes large, that is, when vibrations with relatively long wavelengths occur, the radially processed tip 26a of the flat plate-shaped member 26 comes into contact with the peak portion of the cutting vibration waveform.

[0030] Therefore, as shown in Figure 3, the length S of the dimension from the center of the flat plate-shaped member 26 to the cutting edge exhibits a damping effect even for relatively long vibration wavelengths corresponding to within 1 / 4λ of the vibration wavelength, resulting in a good vibration isolation effect (process damping effect). This ensures reliable high-speed machining, and with a simple configuration, it becomes possible to increase the machining allowance or feed rate, effectively improving production efficiency, while also enabling easy and economical manufacturing.

[0031] On the other hand, if the vibration generated during internal diameter machining by the chip 24 is small, the tip 26a of the flat plate-shaped member 26 in the machining radial direction may not contact the inner circumferential surface Wa of the workpiece W after machining. In this case, the distance T between the tip 26a of the flat plate-shaped member 26 in the machining radial direction and the inner circumferential surface Wa of the workpiece after machining is set within the range of 3 microns (μm) ≤ T ≤ 10 microns (μm), more preferably within the range of 5 microns (μm) ≤ T ≤ 10 microns (μm). This has the advantage of providing a dynamic pressure damping effect by the coolant liquid.

[0032] Here, if the spacing T is less than 3 microns, a good vibration damping effect can be obtained, but the process of setting the spacing T becomes considerably complicated. On the other hand, if the spacing T exceeds 10 microns, there is a problem in that a good vibration damping effect and a good dynamic pressure damping effect cannot be obtained. Furthermore, if the spacing T is 5 microns or more, there is the advantage that the process of setting the spacing T is further simplified.

[0033] Next, when the cutting edge (tip tip 24a) of the tip 24 wears down due to machining, the tip 24 is repositioned (corrected) outward in the machining radial direction via the operating mechanism 30, as shown in Figure 3. Specifically, when the adjustment bolt 50 is rotated in the forward direction, the first threaded portion 52a is screwed into the threaded hole 48b of the tapered end member 48, and the second threaded portion 52b is screwed into the second bolt hole 18b of the cartridge mounting recess 16.

[0034] In this case, the pitch of the first threaded portion 52a is set to a larger value than the pitch of the second threaded portion 52b, and when the adjustment bolt 50 is rotated in the forward direction, the pitch difference pushes the tapered end member 48 upward in a direction away from the bottom surface 16a. The tapered surface 48a of the tapered end member 48 is in contact with the inclined surface 24c of the tip 24, and as the tapered end member 48 is pushed upward, the tip 24 is pushed outward in the machining radial direction, thereby adjusting the position of the tip 24. Here, by setting the pitch difference between the first threaded portion 52a and the second threaded portion 52b, and setting the taper angle of the tapered surface 48a provided on the tapered end member 48, the tip 24 can be adjusted outward in the machining radial direction in micron units.

[0035] Furthermore, there are cases where it is necessary to adjust the position of the flat plate member 26 outward in the machining radial direction. In such cases, with the fixing bolt 28 loosened from the first bolt hole 18a, it is possible to adjust the position of the flat plate member 26 outward in the machining radial direction by the difference in dimension between the diameter of the fixing bolt 28 and the opening diameter of the hole 36. Also, if the R shape of the machining radial tip portion 26a provided on the flat plate member 26 is not appropriate, it can be easily replaced with another flat plate member 26 having a different R shape or polygonal shape. As a result, it becomes possible to change various flat plate members 26 as needed, eliminating the need to change the structure of the boring bar 12 itself, resulting in an economical and highly versatile design.

[0036] Next, the process of fixing the tip 24 will be described. The tip 24 is guided to the mounting position by inserting the head 28a of the fixing bolt 28 into the guide hole 32. Then, the clamp block 38 is pressed against the tip 24. As shown in Figure 4, the curved projection 44 of the clamp block 38 engages with the tapered hole 34 of the tip 24, while the claw portion 46 engages with the clamp recess 22 of the first wall surface 14a. Furthermore, a clamp bolt 41 is inserted into the stepped hole 40 of the clamp block 38, and the clamp bolt 41 is screwed into the clamp bolt hole 20.

[0037] In this configuration, the clamp bolt hole 20 is inclined at an angle γ toward the third wall surface 14c with respect to a vertical line V whose axis is perpendicular to the first wall surface 14a. Consequently, the clamp block 38 is pressed against the inside (axial direction) of the boring bar 12, with the curved surface of the curved projection 44 pressed against the inner wall surface of the tapered hole 34 of the tip 24, while the inclined surface 46a of the claw portion 46 is pressed against the inclined surface 22a of the clamp recess 22. As a result, the tip 24 is firmly held by the clamp block 38, as if being pulled in the axial direction.

[0038] Although not shown in the diagram, multiple chips 24 and flat plate-shaped members 26 can be arranged on a single boring bar 12. This allows for torque flattening by multiple cutting edges and process damping effects by multiple cutting edges, preventing chatter and further improving machining accuracy such as roundness.

[0039] Figure 7 is an explanatory cross-sectional view of the main part of the tip side of the boring bar 12a that constitutes the processing apparatus 60 according to the second embodiment of the present invention. Note that the same reference numerals are used for the same components as those of the boring bar 12 (shown in Figure 3) of the processing apparatus 10 according to the first embodiment, and their detailed descriptions are omitted. Similarly, detailed descriptions are omitted for the third embodiment described below.

[0040] A cartridge mounting recess 16 provided at the tip of the boring bar 12a is fitted with an internal diameter machining tip (cutting tool) 62. The tip 62 has a tip (machining point) 62a that protrudes furthest outward in the machining radial direction, and a first relief surface 62b set at a first tip relief angle α1 and a second relief surface 62c set at a second tip relief angle α2 are provided extending backward from the tip 62a in the machining direction. Preferably, a positive tip 62 is used in which the first tip relief angle α1 is, for example, around 1 degree and the second tip relief angle α2 is, for example, up to 8 degrees.

[0041] In this second embodiment, a process damping effect is obtained when the peak portion of the workpiece W, which has expanded due to the elastic restorative action that occurs immediately after machining, comes into contact with the first flank surface 62b of the tip 62. Furthermore, when vibrations with relatively long wavelengths occur, the tip portion 26a of the flat plate-shaped member 26 in the machining radial direction comes into contact with the peak portion of the cutting vibration waveform. As a result, high-speed machining is reliably performed, production efficiency is effectively improved with a simple configuration, and it becomes possible to manufacture the product easily and economically, thus obtaining the same effects as in the first embodiment described above.

[0042] Figure 8 is an explanatory cross-sectional view of the main part of the tip side of the boring bar 12b that constitutes the processing apparatus 70 according to the third embodiment of the present invention.

[0043] A cartridge mounting recess 16 provided at the tip of the boring bar 12b is fitted with an internal diameter machining tip (cutting tool) 72 and a flat plate-shaped member 74. The tip 72 has a tip (machining point) 72a, and a relief surface 72b is provided extending from the tip 72a towards the rear in the machining direction, set at a tip relief angle α3. As the tip 72, a positive tip is used with a tip relief angle α3 of several degrees or more, up to about 11 degrees. The flat plate-shaped member 74 is set in a rectangular shape corresponding to the shape of the tip 72, and has a substantially trapezoidal cross-section in which the thickness in the machining direction gradually increases outward in the machining radial direction.

[0044] In this third embodiment, when a chip 72 with a large chip relief angle α3 is used, a flat plate-shaped member 74 whose thickness in the machining direction gradually increases outward in the machining radial direction is superimposed on the chip 72. As a result, the chip 72 has a relatively small relief angle, which provides a good process damping effect, as well as the same effects as in the first embodiment described above. When increasing the relative relief angle of the chip, a flat plate-shaped member (not shown) whose thickness in the machining direction gradually decreases outward in the machining radial direction can be used. [Explanation of Symbols]

[0045] 10, 60, 70… Processing equipment 12, 12a, 12b… Boring bars 14a~14d...Wall surface 16...Recess for cartridge mounting 16a...Bottom surface 24, 62, 72...Tip 24a, 62a, 72a... Tip 24b, 62a, 62b, 72b... Relief surfaces 26, 74... Flat plate-shaped members 26a... Radial tip of the machined part 28... Fixing bolt 30...Operating mechanism 38...Clamp block 48...Tapered insert member 50...Adjustment bolt

Claims

1. Bowling bar and A cutting tool for internal diameter machining is detachably attached to the boring bar via a clamping mechanism, A flat plate-shaped member is detachably attached to the boring bar, positioned behind the relief surface of the cutting tool, A fixing mechanism for fixing the flat plate-shaped member to the boring bar so as to be positionable in the direction of the machining diameter by the cutting tool, Equipped with, The processing apparatus is characterized in that the distance between the leading edge of the flat plate-shaped member in the processing radial direction and the inner circumferential surface of the workpiece after processing by the cutting tool is set to a range of 3 microns to 10 microns.

2. The processing apparatus according to claim 1, characterized in that at least a portion of the leading edge of the flat plate-shaped member in the processing radial direction is configured to have a cross-sectional radius shape or a polygonal shape.

3. A processing apparatus according to claim 1 or 2, characterized in that the thickness of the flat plate-shaped member in the processing direction by the cutting tool is gradually reduced or gradually increased outward in the processing radial direction.

4. A machining apparatus according to claim 1, characterized in that the cutting tool is provided with an operating mechanism capable of correcting its position in the machining diameter direction.

5. Bowling bar and A cutting tool for internal diameter machining is detachably attached to the boring bar via a clamping mechanism, A flat plate-shaped member is detachably attached to the boring bar, positioned behind the relief surface of the cutting tool, A fixing mechanism for fixing the flat plate-shaped member to the boring bar so as to be positionable in the direction of the machining diameter by the cutting tool, In a processing apparatus equipped with, A method for generating process damping in a machining apparatus, characterized in that the distance between the radially processed tip of the flat plate-shaped member and the inner circumferential surface of the workpiece after machining by the cutting tool is set to a range of 3 microns to 10 microns, thereby generating process damping at the radially processed tip.

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